In the lighting industry one of the methods used to improve the contrast at the task surface involves controlling the distribution of light. Normally a fluorescent lamp provides the light in a luminaire and the distribution of light is controlled by positioning a lighting panel between the fluorescent lamp and a task surface. An example of a lighting panel embodying such an implemented method is illustrated in U.S. Pat. No. 3,794,829, issued to I. G. Taltavull. Such a lighting panel critically reflects the undesired portion of light and refracts the desired portion of light within a control range. A difficulty with such a lighting panel is that the panel is not efficient in that it does not directly use the undesired portion of light. Accordingly, such a panel can not operate at optimum efficiency.
A recent development in the lighting industry is a device for radially polarizing substantially collimated light and then radially refracting the polarized light. Such a device has the advantage of improving the contrast at the task surface to obtain relatively high efficiency, thereby permitting a lesser amount of light at the source while providing sufficient working illumination at the task surface. An example of such a device is set forth in related application Ser. No. 473,857, now U.S. Pat. No. 3,912,921.